Any bulk email sender will offer you the possibility to send a certain amount of emails. Start the application, access the configuration menu and set up the SMTP server then use the lists management option and load the TXT file. In the composing section, add your letter or simply paste the contents of the HTML file. Click Send and wait for the software to send the emails and that's it. This is the general process for every bulk email sender available for Windows, Mac, Linux, etc.